3490 四履帶搜救機器人機械結(jié)構(gòu)設(shè)計—行星減速器設(shè)計,履帶,搜救,機器人,機械,結(jié)構(gòu)設(shè)計,行星減速器,設(shè)計 河南理工大學(xué)萬方科技學(xué)院本科畢業(yè)設(shè)計（論文）開題報告題目名稱四履帶搜救機器人機械結(jié)構(gòu)設(shè)計—行星減速器設(shè)計學(xué)生姓名 秦豐文 專業(yè)班級 08 級機械設(shè)計 2 班 學(xué)號 0828070094一、 選題的目的和意義：地震、火災(zāi)、礦難等災(zāi)難發(fā)生后,在廢墟中搜尋幸存者,給予必要的醫(yī)療救助,并盡快救被困者是救援人員面臨的緊迫任務(wù)。實際經(jīng)驗表明,超過 48 小時后被困在廢墟中的幸存者存活的概率變得越來越低。由于災(zāi)難現(xiàn)場情況復(fù)雜,在救援人員自身安全得不到保證的情況下是很難進入現(xiàn)場開展救援工作的,此外,廢墟中形成的狹小空間使搜救人員甚至搜救犬也無法進入。災(zāi)難搜救機器人可以很好地解決上述問題。機器人可以在災(zāi)難發(fā)生后第一時間進入災(zāi)難現(xiàn)場尋找幸存者,對被困人員提供基本的醫(yī)療救助服務(wù),進入救援人員無法進入的現(xiàn)場搜集有關(guān)信息并反饋給救援指揮中心等。近年來,為了滿足救援工作的需要,國內(nèi)外很多研究機構(gòu)開展了大量的研究工作,可在災(zāi)難現(xiàn)場廢墟中狹小空間內(nèi)搜尋的各類機器人如可變形多態(tài)機器人、蛇形機器人等相繼被開發(fā)出來。通過國內(nèi)外災(zāi)難搜救機器人最新研究成果及近年來災(zāi)難現(xiàn)場的實際使用情況的基礎(chǔ)上,根據(jù)現(xiàn)場使用的經(jīng)驗教訓(xùn)提出了災(zāi)難救援機器人需要解決的一些關(guān)鍵技術(shù)問題 ，指出了災(zāi)難救援機器人的發(fā)展趨勢。2二、 國內(nèi)外研究綜述：近十年來,尤其是“911”事件之后,美國、日本等西方發(fā)達國家在地震、火災(zāi)等救援機器人的研究方面做了大量的工作,研究出了各種可用于災(zāi)難現(xiàn)場救援的機器人。以牽引和運動方式的不同搜救機器人主要可分為以下幾類:1.履帶式搜救機器人履帶式機器人是為了滿足軍事偵察、拆除危險物等作業(yè)的需要,在傳統(tǒng)的輪式移動機器人的基礎(chǔ)上發(fā)展起來的。他們主要是為了滿足軍事需要而開發(fā)的,體積普遍偏大,不太適合在倒塌的建筑物廢墟中狹小空間內(nèi)搜尋幸存者。2.可變形(多態(tài)) 搜救機器人為了能進入狹小空間展開搜救工作,要求機器人的體積要盡可能小,但體積小了搜索視野就會受到限制,為了解決這一矛盾,近年來在傳統(tǒng)牽引式搜救機器人平臺基礎(chǔ)上,研制出了形態(tài)可變的履帶式多態(tài)搜救機器人。美國iRobot 公司生產(chǎn)的PackBot 系列機器人, PackBot 機器人有一對鰭形前肢,這對鰭形前肢可以幫助在崎嶇的地面上導(dǎo)航,也可以升高感知平臺以便更好地觀察。加拿大Inuktun 公司MicroVGTV 多態(tài)搜救機器人,他可以根據(jù)搜索通道的大小及搜尋范圍的遠近靈活地調(diào)整形狀和尺寸。3. 仿生搜救機器人雖然履帶式可變形多態(tài)機器人可根據(jù)搜索空間的大小改變其形狀和尺寸,但受驅(qū)動方式的限制,其體積不可能做得很小。為了滿足對更狹小空間搜索的需要,人們根據(jù)生態(tài)學(xué)原理研制出了各種體積更小的仿生機器人,其中蛇形機器人就是其中很重要的一類CMU 研制的安裝在移動平臺上的蛇形機器人,為日本大阪大學(xué)研制的蛇形機器人。我國中國科學(xué)院沈陽自動化研究所,國防科技大學(xué),北京航空航天大學(xué)等單位也都相繼研制出了類似的蛇形機器人系統(tǒng)。為美國加州大學(xué)伯克利分校研制的身高不3足3 cm 的蒼蠅搜救機器人。隨著技術(shù)的不斷成熟,相信蛇形、蠅形等仿生機器人會在災(zāi)難搜救工作中發(fā)揮越來越大的不可替代的特殊作用。三、 畢業(yè)設(shè)計（論文）所用的主要技術(shù)與方法：1.通過圖書館查找資料2.通過網(wǎng)絡(luò)查找資料3.通過各種報刊期刊查找資料4.新聞電視等媒體報道的信息5.老師、同學(xué)、朋友提供的信息四、 主要參考文獻與資料獲得情況：[1] 上海廣茂達伙伴機器人有限公司. 能力風(fēng)暴智能機器人 VJC1.6 開發(fā)版使用手冊[J]. 現(xiàn)代電子技術(shù)，2005.[2] 肖松雷，華劍 . 機器人在搜索救援中的應(yīng)用[J]. 機器人技術(shù)與應(yīng)用，2006.[3] 曹祥康，謝存 . 我國機器人發(fā)展歷程[J]. 機器人技術(shù)與應(yīng)用，2008.[4]王勇，朱華，王永勝. 煤礦救災(zāi)機器人研究現(xiàn)狀及需要重點解決的 技術(shù)問題[J].煤礦機械，2007.[5] 上海廣茂達伙伴機器人有限公司. 擴展卡使用手冊修改（總）[J].機器人技術(shù)與應(yīng)用，2003.[6]柏龍，葛文杰，陳曉紅，張銘. 用于行星探測的跳躍機器人研究[J]，機器人，2009.[7]叢爽，錢輝環(huán). 廣茂達機器人幾個實際應(yīng)用問題的解決方案[J]. 機器人技術(shù)與應(yīng)用，2003.[8]趙長富，李千新. 傳感器在工業(yè)機器人中的應(yīng)用[J]. 組合機床與自動化加工技術(shù)，1987.[9] 張福學(xué). 機器人傳感器(上)[J] . 測控技術(shù)，1987.4五、 畢業(yè)設(shè)計（論文）進度安排（按周說明）第六周 討論畢業(yè)論文的各項問題，并確定論文題目。第七周 與指導(dǎo)老師討論并確定論文框架。第八周 指導(dǎo)老師對開題報告格式的指導(dǎo),并查找有關(guān)論文的資料。第八周 與指導(dǎo)老師討論參考文獻的事宜。第九周 著手開始寫畢業(yè)論文、指導(dǎo)老師中期檢查并填寫中期檢查表。第十周 找指導(dǎo)老師解決寫畢業(yè)論文時遇到的問題。第十一周 繼續(xù)撰寫畢業(yè)論文。第十二周 完成畢業(yè)論文初稿。第十三周 與指導(dǎo)老師討論并修改畢業(yè)論文。第十四周 裝訂上交論文及材料六、 指導(dǎo)教師審批意見：指導(dǎo)教師： （簽名）年 月 日 河南理工大學(xué)萬方科技學(xué)院本科畢業(yè)設(shè)計（論文）開題報告題目名稱四履帶搜救機器人機械結(jié)構(gòu)設(shè)計—行星減速器設(shè)計學(xué)生姓名 秦豐文 專業(yè)班級 08 級機械設(shè)計 2 班 學(xué)號 0828070094一、 選題的目的和意義：地震、火災(zāi)、礦難等災(zāi)難發(fā)生后,在廢墟中搜尋幸存者,給予必要的醫(yī)療救助,并盡快救被困者是救援人員面臨的緊迫任務(wù)。實際經(jīng)驗表明,超過 48 小時后被困在廢墟中的幸存者存活的概率變得越來越低。由于災(zāi)難現(xiàn)場情況復(fù)雜,在救援人員自身安全得不到保證的情況下是很難進入現(xiàn)場開展救援工作的,此外,廢墟中形成的狹小空間使搜救人員甚至搜救犬也無法進入。災(zāi)難搜救機器人可以很好地解決上述問題。機器人可以在災(zāi)難發(fā)生后第一時間進入災(zāi)難現(xiàn)場尋找幸存者,對被困人員提供基本的醫(yī)療救助服務(wù),進入救援人員無法進入的現(xiàn)場搜集有關(guān)信息并反饋給救援指揮中心等。近年來,為了滿足救援工作的需要,國內(nèi)外很多研究機構(gòu)開展了大量的研究工作,可在災(zāi)難現(xiàn)場廢墟中狹小空間內(nèi)搜尋的各類機器人如可變形多態(tài)機器人、蛇形機器人等相繼被開發(fā)出來。通過國內(nèi)外災(zāi)難搜救機器人最新研究成果及近年來災(zāi)難現(xiàn)場的實際使用情況的基礎(chǔ)上,根據(jù)現(xiàn)場使用的經(jīng)驗教訓(xùn)提出了災(zāi)難救援機器人需要解決的一些關(guān)鍵技術(shù)問題 ，指出了災(zāi)難救援機器人的發(fā)展趨勢。2二、 國內(nèi)外研究綜述：近十年來,尤其是“911”事件之后,美國、日本等西方發(fā)達國家在地震、火災(zāi)等救援機器人的研究方面做了大量的工作,研究出了各種可用于災(zāi)難現(xiàn)場救援的機器人。以牽引和運動方式的不同搜救機器人主要可分為以下幾類:1.履帶式搜救機器人履帶式機器人是為了滿足軍事偵察、拆除危險物等作業(yè)的需要,在傳統(tǒng)的輪式移動機器人的基礎(chǔ)上發(fā)展起來的。他們主要是為了滿足軍事需要而開發(fā)的,體積普遍偏大,不太適合在倒塌的建筑物廢墟中狹小空間內(nèi)搜尋幸存者。2.可變形(多態(tài)) 搜救機器人為了能進入狹小空間展開搜救工作,要求機器人的體積要盡可能小,但體積小了搜索視野就會受到限制,為了解決這一矛盾,近年來在傳統(tǒng)牽引式搜救機器人平臺基礎(chǔ)上,研制出了形態(tài)可變的履帶式多態(tài)搜救機器人。美國iRobot 公司生產(chǎn)的PackBot 系列機器人, PackBot 機器人有一對鰭形前肢,這對鰭形前肢可以幫助在崎嶇的地面上導(dǎo)航,也可以升高感知平臺以便更好地觀察。加拿大Inuktun 公司MicroVGTV 多態(tài)搜救機器人,他可以根據(jù)搜索通道的大小及搜尋范圍的遠近靈活地調(diào)整形狀和尺寸。3. 仿生搜救機器人雖然履帶式可變形多態(tài)機器人可根據(jù)搜索空間的大小改變其形狀和尺寸,但受驅(qū)動方式的限制,其體積不可能做得很小。為了滿足對更狹小空間搜索的需要,人們根據(jù)生態(tài)學(xué)原理研制出了各種體積更小的仿生機器人,其中蛇形機器人就是其中很重要的一類CMU 研制的安裝在移動平臺上的蛇形機器人,為日本大阪大學(xué)研制的蛇形機器人。我國中國科學(xué)院沈陽自動化研究所,國防科技大學(xué),北京航空航天大學(xué)等單位也都相繼研制出了類似的蛇形機器人系統(tǒng)。為美國加州大學(xué)伯克利分校研制的身高不3足3 cm 的蒼蠅搜救機器人。隨著技術(shù)的不斷成熟,相信蛇形、蠅形等仿生機器人會在災(zāi)難搜救工作中發(fā)揮越來越大的不可替代的特殊作用。三、 畢業(yè)設(shè)計（論文）所用的主要技術(shù)與方法：1.通過圖書館查找資料2.通過網(wǎng)絡(luò)查找資料3.通過各種報刊期刊查找資料4.新聞電視等媒體報道的信息5.老師、同學(xué)、朋友提供的信息四、 主要參考文獻與資料獲得情況：[1] 上海廣茂達伙伴機器人有限公司. 能力風(fēng)暴智能機器人 VJC1.6 開發(fā)版使用手冊[J]. 現(xiàn)代電子技術(shù)，2005.[2] 肖松雷，華劍 . 機器人在搜索救援中的應(yīng)用[J]. 機器人技術(shù)與應(yīng)用，2006.[3] 曹祥康，謝存 . 我國機器人發(fā)展歷程[J]. 機器人技術(shù)與應(yīng)用，2008.[4]王勇，朱華，王永勝. 煤礦救災(zāi)機器人研究現(xiàn)狀及需要重點解決的 技術(shù)問題[J].煤礦機械，2007.[5] 上海廣茂達伙伴機器人有限公司. 擴展卡使用手冊修改（總）[J].機器人技術(shù)與應(yīng)用，2003.[6]柏龍，葛文杰，陳曉紅，張銘. 用于行星探測的跳躍機器人研究[J]，機器人，2009.[7]叢爽，錢輝環(huán). 廣茂達機器人幾個實際應(yīng)用問題的解決方案[J]. 機器人技術(shù)與應(yīng)用，2003.[8]趙長富，李千新. 傳感器在工業(yè)機器人中的應(yīng)用[J]. 組合機床與自動化加工技術(shù)，1987.[9] 張福學(xué). 機器人傳感器(上)[J] . 測控技術(shù)，1987.4五、 畢業(yè)設(shè)計（論文）進度安排（按周說明）第六周 討論畢業(yè)論文的各項問題，并確定論文題目。第七周 與指導(dǎo)老師討論并確定論文框架。第八周 指導(dǎo)老師對開題報告格式的指導(dǎo),并查找有關(guān)論文的資料。第八周 與指導(dǎo)老師討論參考文獻的事宜。第九周 著手開始寫畢業(yè)論文、指導(dǎo)老師中期檢查并填寫中期檢查表。第十周 找指導(dǎo)老師解決寫畢業(yè)論文時遇到的問題。第十一周 繼續(xù)撰寫畢業(yè)論文。第十二周 完成畢業(yè)論文初稿。第十三周 與指導(dǎo)老師討論并修改畢業(yè)論文。第十四周 裝訂上交論文及材料六、 指導(dǎo)教師審批意見：指導(dǎo)教師： （簽名）年 月 日 河南理工大學(xué)萬方科技學(xué)院本科畢業(yè)設(shè)計（論文）中期檢查表指導(dǎo)教師： 鄧樂 職稱： 教授 所在院（系）： 機械與動力工程系 教研室（研究室）： 系部辦公樓 317 題 目 四履帶搜救機器人的結(jié)構(gòu)設(shè)計—行星減速器設(shè)計學(xué)生姓名 秦豐文 專業(yè)班級 08 機設(shè) 2 班 學(xué)號 0828070094一、選題質(zhì)量：1.本題目符合機械設(shè)計專業(yè)的培養(yǎng)目標，能夠充分鍛煉和培養(yǎng)分析問題和實際操作能力，能夠體現(xiàn)綜合訓(xùn)練的要求2.設(shè)計任務(wù)難易程度和工作量適中，符合本科畢業(yè)設(shè)計要求，能在規(guī)定的時間內(nèi)完成。3.所選題目較為新穎，故所收集的資料較少，工作量較大。4.所選題目與實際貼合比較緊密，在實際的救援中也很重要。在設(shè)計過程中，對機器人各個結(jié)構(gòu)和零件的設(shè)計、計算對我來說，是對以往所學(xué)知識的總結(jié)和應(yīng)用，所以能夠滿足綜合訓(xùn)練的要求。但是在設(shè)計過程中，對于我來說還是具有很大的難度，對于這方面的涉足也并不是很多，并且且這方面的資料也是比較少，所以這對我來說也是一個挑戰(zhàn)。二、開題報告完成情況：根據(jù)自己在各方面資料的收集和整理，通過對可行性的分析，結(jié)合老師給的題目的選擇，我完成了這次設(shè)計的選題。在選題結(jié)束之后，通過自己認真查閱相關(guān)的資料，最后結(jié)合本身的實際情況和設(shè)計的時間任務(wù)完成了開題報告。經(jīng)過指導(dǎo)老師同意，完成開題報告，同意開題。2三、階段性成果：1.通過對搜救機器人的了解，再加上指導(dǎo)老師對我們的講解，算是對其有了一個大概的了解。前期階段主要是對有關(guān)于搜救機器人的各方面的文獻和資料進行搜集，為以后的設(shè)計做了必要的準備。2.中期階段主要是依據(jù)參考資料，從上面找到一些關(guān)于關(guān)于搜救機器人結(jié)構(gòu)設(shè)計的信息，首先對其結(jié)構(gòu)有了大致的了解，其次是已有了大概的設(shè)計方法，并開始了一些基本的結(jié)構(gòu)設(shè)計。3.正在進行裝配圖的 CAD 畫圖和進行設(shè)計說明書的部分工作。4.正在進行我在小組中所負責的主體部分的設(shè)計，包括履帶、齒輪和軸等部件的選材以及數(shù)據(jù)計算等工作。四、存在主要問題：1、這次設(shè)計對我來說是個比較大挑戰(zhàn)，和同學(xué)的配合剛開始有很多不恰當?shù)牡胤?，但隨著設(shè)計的進行和不斷的討論磨合，也逐漸克服了這一問題。2、搜救機器人設(shè)計對我是個新題，并且在搜索資料方面發(fā)現(xiàn)，關(guān)于搜救機器人的資料也并不是很多。3、設(shè)計過程中關(guān)于自己所設(shè)計的方面不是太明確，經(jīng)過和同組同學(xué)的商量明確了自己的任務(wù)。4.由于資料過于稀少，沒有可參考的材料，在計算數(shù)據(jù)、校核、選材方面還有很大的不明之處。3五、指導(dǎo)教師對學(xué)生在畢業(yè)實習(xí)中，勞動、學(xué)習(xí)紀律及畢業(yè)設(shè)計（論文）進展等方面的評語指導(dǎo)教師： （簽名）年 月 日Mobile platform of rocker-type coalmine rescue robotLI Yun wang *, GE Shirong, ZHU Hua, FANG Haifang, GAO JinkeSchool of Mechanical and Electrical Engineering, China University of Mining & Technology, Xuzhou 221008, ChinaAbstract: After a coal mine disaster, especially a gas and coal dust explosion, the space-restricted and unstructured underground terrain and explosive gas require coal mine rescue robots with good obstacle-surmounting performance and explosion-proof capability. For this type of environment, we designed a mobile platform for a rocker-type coal mine rescue robot with four independent drive wheels. The composition and operational principles of the mobile platform are introduced, we discuss the flameproof design of the rocker assembly, as well as the operational principles and mechanical structure of the bevel gear differential and the main parameters are provided. Motion simulation of the differential function and condition of the robot running on virtual, uneven terrain is carried out with ADAMS. The simulation results show that the differential device can maintain the main body of the robot at an average angle between two rockers. The robot model has good operating performance. Experiments on terrain adaptability and surmounting obstacle performance of the robot prototype have been carried out. The results indicate that the prototype has good terrain adaptability and strong obstacle-surmounting performance.Keywords: coal mine; rescue robot; rocker suspension; differential; explosion-proof design1 IntroductionIn the rescue mission of a gas and coal dust explosion ,rescuers easily get poisoned in underground coal mines full of toxic gases, such as high-concentrationCH4 and CO, if ventilation and protection are not up to snuff. Furthermore, secondary or multiple gas explosions may be caused by extremely unstable gases after such a disaster and may cause casualties among the rescuers [1]. Therefore, in order to perform rescue missions successfully, in good time and decrease casualties, it is necessary to develop coal mine rescue robots. They are then sent to enter the disaster area instead of rescuers and carry out tasks of environmental detection, searching for wounded miners and victims after the disaster has occurred. The primary task of the robots in rescue work is to enter the disaster area. It is difficult for robots to move into restricted spaces and unstructured underground terrain, so these mobile systems require good obstacle-surmounting performance and motion performance in this rugged environment [2]. The application of some sensors used for terrain identification are severely restricted by low visibility and surroundings full of explosive gas and dust; hence, a putative mobile system should, as much as possible, be independent from sensing and control systems[3].Studies of coal mine rescue robots are just beginning at home and abroad. Most robot prototypes are simple wheel type and track robots. The mine exploration robot RATLER, developed by the Intelligent Systems and Robotics Center (ISRC) of Sandia National Laboratories, uses a wheel type mobile system [4]. The Carnegie Mellon University Robot Research Center developed an autonomous mine exploration robot, called “groundhog [5]. Both the mine rescue robot V2 produced by the American Remote Company and the mine search and rescue robot CUMT developed by China University of Mining and Technology, use a two-track fixed type moving system[6-7]. These four prototypes are severely limited in underground coal mines. Rocker type robots have demonstrated good performance on complex terrain. All three Mars rovers, i.e., Sojourner, Spirit and Opportunity used mobile systems with six independent drive wheels[8-9]. Rocker-Bogie, developed by the American JPL laboratory has landed successfully on Mars. The SRR robot from the JPL laboratory with four independent drive and steering wheels consists of a moving rocker assembly system, similar to the four wheel-drive SR2 developed by the University of Oklahoma, USA [10]. Both tests and practical experience have shown that this type of system has good motion performance, can adapt passively to uneven terrain, possesses the ability of self-adaptation and performs well in surmounting obstacles. Given the unstructured underground terrain environment and an atmosphere of explosive gases, we investigated a coalmine rescue robot with four independent drive wheels and an explosion-proof design, based on a rocker assembly structure. We introduce the composition and operational principles of this mobile system, discuss the design method of its rocker assembly and differential device and carried out motion simulation of the kinematic performance of the robot with ADAMS, a computer software package. In the end, we tested the terrain adaptability and performance of the prototype in surmounting obstacles.2 Mobile platform [11-12]As shown in Fig. 1, the mobile platform of the rocker-type four-wheel coal mine rescue robot includes a main body, a gear-type differential device, two rocker suspensions and four wheels. The shell of the differential device is attached to the interior of the main body. The two extended shafts of the differential device are supported by the axle seats in the lateral plate of the main body and connected to the rocker suspensions installed at both sides of the main body. The four wheels are separately connected to the bevel gear transmission at the terminal of the four landing legs. The four wheels are independently driven by a DC motor, installed inside the landing legs of the rocker suspension. A flameproof design ofthe legs has been developed, which includes a flameproof motor cavity and a flameproof connection cavity. Via a cable entry device, the power and control cables of the DC motor are connected to the power and controller of the main body. 2.1 Rocker suspension2.1.1 FunctionThe primary role of the rocker suspension is to provide the mobile platform with a mobile system that can adapt to the unstructured underground terrain, such as rails, steps, ditches and deposit of rock and coal dumps because of the collapse of the tunnel roof after a disaster. By connecting the differential device intermediate between the two rocker suspensions, the four drive wheels can touch the uneven ground passively and the wheels can bear the average load of the robot so that it is able to cross soft terrain. The wheels can supply enough propulsion, which allows the robot to surmount obstacles and pass through uneven terrain.2.1.2 StructureAs shown in Fig. 1, the rocker suspension is composed of a connecting block, landing legs and bevel gear transmissions. The angle between the landing legs on each side of the main body is carefully calibrated. The legs are connected to the connecting block and the terminals, which in turn are connected to the bevel gear transmissions. Fig. 2 illustrates the structure of the landing leg. It is divided into an upper and a bottom section. The bottom section is cylindrical. The DC motor is in the leg and fixed to the connecting cylinder. The motor shaft connects to the bevel gear transmission and the wheel is also connected to the transmission. The upper section has a blind center hole through witch a connection is formed to the bottom section, via a connection cavity. Through the cable entry device of the upper section, the motor power and control cable from the main body of the robot are put into the connection cavity and connect to the wiring terminals which, in turn, connect to the guidance wires in the wire holder. Another end of the guidance wires connects to the motor in the bottom section.2.1.3 Flameproof designA coal mine environment is full of explosive gases; hence, a rescue robot must be designed to be flameproof. The DC motors, for driving each wheel, are installed in the landing legs of the rocker suspensions. At the present low-powered DC motors, available in the market, are of a standard design and not flameproof, hence a flameproof structure for these motors must be designed. Given the structural features of the rocker suspension, it is very much necessary that a flameproof design for the landing legs be carried out.There are two important points to be considered in this flameproof design. First, a flameproof cavity is needed, in which the standard DC motor is installed. Given the flameproof design requirements, a group of flameproof joints should be formed between the motor shaft and the shaft hole. Generally, the motor shaft made by the manufacturer is too short to comply with the requirement of flameproof joints, so the motor shaft needs to be extended. Second, a flameproof connection cavity should be designed to lead the c a- Fig. 1 Rocker-type four-wheel mobile platform Main body Rocker suspension Landing leg Wheel Rocker suspension Connecting block Differential device Bevel gear transmission Axle seat Upper section Wire holder Bottom section DC motor Flameproof joints Flameproof joints Bevel gear transmission Connecting cylinder Shaft sleeve Wheel Cable entry into the connection cavity through a flameproof cable entry device. DC motors, especially brush DC motors, may generate sparks in normal running and when the motor load is high, the working current may be more than 5 A, which exceeds the current limit in Appendix C2 of the National Standard GB3836.2- 2000 of China. Therefore, the motor power and control cable cannot be directly in the connection cavity。Given these requirements, the landing legs have been designed as flameproof units, as shown in Fig. 2. An elongated shaft sleeve has been assembled from the motor shaft, with the same inside radius as that of the motor shaft and this is how the motor shaft is extended. The front flange of the motor is fixed to the intermediate plate of the connecting cylinder. The motor shaft with the shaft sleeve passes through the center hole embedded with a brass bush and then connects to the input gear of the bevel gear transmission at the end of the bottom section of the landing leg. Therefore, flameproof joints are formed between the motor shaft and the shaft sleeve, as well as between the shaft sleeve and the brass bush. The terminal of the bottom section of the leg connects to the connecting cylinder and a flameproof joint is formed between the external cylindrical surface of the terminal and the inner cylinder surface of the connecting cylinder.There is also a flameproof connection cavity in the upper section of the leg. In order to save space, the guidance wire is sealed together with the wire holder using a sealant. The seat of the guide wire is installed in the hole of the upper section of the landing leg. Another flameproof joint is formed between the wire holder and the hole. The cavity of the upper section connects to the rabbet structure of the bottom section, with yet another flameproof joint. There is a flameproof cable entry device at the end of the upper section of the landing leg. Hence, a flameproof connection cavity is formed in the upper section of the leg. Based on the structure described, the standard DC motor was installed in the flameproof cavity of the bottom section of the leg. The power and control cables of the motor connect to the flameproof connection cavity of its upper section through a wire holder. Moreover, the cable from the flameproof main body of the robot connects to the connection cavity via the flameproof cable entry device. Thus, the flameproof design of the landing leg of the rocker suspensionsection was completed.2.2 Differential device[13-15]2.2.1 Characteristics of the differential mechanism The differential mechanism of a rocker-type robot is a motion transfer mechanism with two degrees of freedom, which can transform the two rotating inputs into a rotating output. The output is the linear mean values of the two inputs. If we let 1 ω and 2 ω be two angular velocity inputs, ω the angular velocity Two rotational input components connect to the left and the right rocker suspension of the robot and the output component connects to the main body of the robot. In this way, the swing angles of the left and right rocker suspensions are averaged by the differential mechanism and the mean value, transformed into the swing angle (pitching angle) of the main body, is the output. It is effective in decreasing the swing of the main body and thus reduces the terrain effect. Taking the main swing angle of the main body as input and the swing angles of the left and the right rocker suspension as outputs, the rotational input is decomposed into two different rotational outputs. If the output is the mean value of two inputs, it is helpful to allocate the average weight of the body to each wheel which can adjust its position passively alone in the terrain.Given the characteristics and operating requirements of differential mechanisms, a bevel gear type differential mechanism has been designed. We have analyzed the working principle of the bevel gear differential mechanism and present its detailed structural design.2.2.2 Principle of the bevel gear differential mechanismFig. 3 shows the schematic diagram of the bevel gear differential mechanism. Two semi-axle bevel gears 1 and 2 mesh with the planetary bevel gear 3 orthogonally. Carrier H connects to planetary bevel gear 3 coaxially. Let the angular velocities of gears 1,It can clearly be seen that this bevel gear differential mechanism can be used in the rocker-type mobile robot.2.2.3 Bevel gear differential deviceGiven the above principle of a bevel gear differential mechanism, we designed such a bevel gear differential device, shown in Fig. 4. Fig. 4a is the outline of the differential device, and Fig. 4 bitsinte rnalstructure .This bevel gear differential device is composed of a shell, end covers, an axle base, semi-axle bevel gears, planetary bevel gears, a connecting shaft, etc. The end covers and axle beds connect to the shell by screws. In the shell, two planetary bevel gears are coaxial and symmetrically installed at the connecting shaft, with the shaft terminals supported at the end covers. There are bearings between the connecting shaft and bevel gears. The circlips are installed on the connecting shaft to limit the load on the bearings. Two semi-axle bevel gears are housed in the two axle beds separately, two axle beds are fixed on the shell symmetrically and two semi-axle bevel gears mesh with two planetary bevel gears orthogonally. The twoaxle bases have the same structure. The semi-axle bevel gears are located by the bearings, shaft sleeve and circlips in the axle beds. When the differential device is installed on the robot, the two axles of the left and right semi-axle bevel gears are connected to the left and right rockers. The shell of the differential is fixed on the main body of the robot.3 Mobile platform Test3.1 Simulation testAccurate, simulated 3D model of the robot was imported into the ADAMS software. Using the kinematic pairs in the joints database of the ADAMS/View, the movement of each part of the simulation model is constrained. For simulating the differential action of differential devices acting on the robot body, a revolute joint between the left and right rockers of the model and the “Ground” is established. Random moments of forces are exerted to the left and right rockers to simulate the rough action of the terrain on the rockers. For simulating the movements of the differential device accurately, contact forces are exerted to the pair of gears of the differential device. After corresponding marker points on the robot areestablished, the swinging angles of the left and right rockers and the robot body are measured and the curves of the swinging angles along with the time are obtained via the ADAMS/Post processor module, shown in Fig. 6. Curves 1 and 2 are swing angle curves of the two rockers, while curve 3 is the swing angle curve of the main body.? The bevel gear differential device can average the swing angles of the right and left rockers, and the average value is the swing angle of the main body. The gap between two teeth and other factors cause the return difference of the gear drive, so when the main body is swinging at the early start-up and through the zero angle, there is a slight swinging angle deviation between the simulated and theoretical values.Typical steps, channels, slopes and other complex terrain models are built in the Solid Works software. For testing the traffic ability characteristics and ride comfort of the four wheel robot, all-terrains models are imported into the ADAMS software[16-17]. Then the joints and restraints are rebuilt, Contact Force between the terrain and the wheels is exerted and torque is exerted to each wheel. The running condition of the robot is simulated on the complex terrain, as shown in Fig. 7a. The vertical displacement, velocity and acceleration curves of the centroid of the body and the centers of the four wheels can be obtained, as shown in Figs. 7b~7d. According to the curves, the curve of the centroid displacement of the main body (main body d curve) is very smooth and the velocity and acceleration of the main body is approximately the mean of that of the four wheels. The simulation results show that the mobile platform of the robot has good trafficability and rides comfortably on the complex terrain.3.2 Prototype testIn order to verify the performance of the robot in surmounting obstacles and adapting to a complex terrain, an obstacle-surmounting test of the robot was carried out on a simple obstacle course built in the laboratory and on a complex outdoor terrain bestrewn with messy bricks and stones. Fig. 8 shows the video image of the robot when moving on the complex terrain. The tests indicate that the four drive wheels of the robot can passively keep contact with the uneven ground and the robot performed well in surmounting obstacles. When moving on uneven ground, the swing angle of the main body was small and the differential device could effectively reduce the effect ofthe changing terrain to the main body. One side of the robot can cross a 260 mm-high obstacle. Only large obstacles between the landing legs of the rockers appear to block progress. The performance in surmounting obstacles by the four wheels of the robots is clearly better than that of a track-type robot of the same size.4 Conclusions1) Coal mine accidents, especially gas and coal dust explosions, occur frequently. Therefore, it is necessary to investigate and develop coal mine rescue robots that can be sent into mine disaster areas to carry out tasks of environmental detection and rescue missions after disasters have occurred, instead ofsending rescuers which might become exposed to danger.2) An underground coal mine environment presents a space-restricted, unstructured terrain environment, with a likely explosive gas atmosphere after a disaster. Hence, any mobile system would require a high motion performance and obstacle-surmounting performance on complex terrain.3) Given an unstructured underground terrain environment and an explosive atmosphere, we investigated an explosion-proof coal mine rescue robot with four independent drive wheels, based on a rocker type structure. Our simulation and test results indicate that the robot performs satisfactorily, can passively adapt to uneven terrain, is self-adaptive and performs well in surmounting obstacles.4) In our study, we only investigated the rocker type mobile platform of a coal mine rescue robot. In order to adapt to the underground coal mine environment, we also carried out a flameproof design for the main body. It was necessary to improve the rocker suspensions in order for the robot to be able to adjust the angle between two landing legs automatically, sothat the height of the center of gravity of th